Add HTTPS Proxy Support for Fetch Requests

[GwiYeong]

Description:

This PR introduces support for HTTPS proxy configuration in fetch requests. The changes allow the application to route HTTP requests through a specified proxy server, enhancing security and network configuration flexibility.

Changes:

1. Proxy Configuration:

• Added logic to check for https_proxy or HTTPS_PROXY environment variables.
  Implemented a custom fetch function that utilizes undici's ProxyAgent to route requests through the specified proxy.

2. Request Initialization:

• Modified the request initialization to include the dispatcher property with ProxyAgent when a proxy is detected.

Code Changes:

• File: src/action.ts
  • Added import statements for undiciFetch, ProxyAgent, and RequestInit from undici.
  • Introduced a new conditional block to check for https_proxy environment variables and configure the fetch requests accordingly.
  • Updated the Octokit initialization to include the custom fetch function when a proxy is used.

Example Usage:

To utilize the proxy support, set the https_proxy or HTTPS_PROXY environment variable before running the action:

jobs:
  deploy:
    steps:
      - name: Deploy
        uses: fjogeleit/yaml-update-action@main
        env:
          HTTPS_PROXY: http://dev-lypwg01-001.yahoo-net.jp:8080
    ...

[fjogeleit]

thanks for your contribution and sorry for the late response, will try to take a deeper look this week.

Is there a reason that you did not add undici to the package,json as dependency? And why you used an env var instead of an action value?